function s1_goto_dir(){
	
cd "$1" || exit 1

}

function s2_touch_empty_file_with_given_name(){

touch "$1"

}

function s3_make_directories(){

mkdir  projects

cd projects

mkdir git

mkdir backup

}

s4_create_6_files(){

touch projects/linux{1,2}_{centos,redhat,c_programming}

}

s5_make_directories_in_git(){

mkdir projects/git/linux1 projects/git/linux2

}

s6_move_files_to_dir_l_or_2(){

mv projects/linux1_* projects/git/linux1/ 

mv projects/linux2_* projects/git/linux2/

}

s7_create_package_and_compress(){

cd projects

tar -czvf backup/git.tar.gz git/

}

s8_delete_dir_git(){

rm -rf projects/git

}

function s9_recover_from_git_tar_gz_backup(){

tar -zxvf projects/backup/git.tar.gz -C ./projects/

}

function s10_create_package_and_compress(){

cd projects

tar -jcvf backup/git.tar.bz2 git/

}

function s11_find_and_sort_alphabetically_all_created_files_and_dirs(){

find ./projects -type f -o -type d | sort

}

function s12_get_next_15_minutes_boundary(){

courrent_timestamp=$(date +%s)

rounded_timestamp=$(( (current_timestamp +750) / 900 * 900))

current_timestamp=$(date +%s)

interval_start_timestamp=$(( (current_timestamp / 900) * 900))

next_interval_timestamp=$(( interval_start_timestamp + 900))

next_15min_boundary=$(date -d @"$next_interval_timestamp" +%Y-%m-%d_%H:%M:%S)

echo "$next_15min_boundary"

}

